DE9313930U1 - Devices for influencing a grain spectrum in high-speed classifier mills - Google Patents

Description

K&K GmbH

Devices for influencing the grain spectrum in classifying mills

The invention relates to devices for influencing the grain spectrum below the upper grain limit of a powder in high-speed classifying mills with the aid of a "static classifier" between the grinding zone and a dynamic classifier, as well as changes in the area of the actual grinding zone.

The requirements in the area of crushing technology with regard to a specific grain spectrum below the upper limit grain size, already during the grinding or crushing process, are becoming increasingly higher. So-called high-speed "sifter mills" are now able to produce "powder" with a defined upper limit grain size.

However, the lower, middle or upper range of the grain spectrum can currently hardly be influenced with these "classifying mills".

When producing, treating and/or processing powders, increasingly higher and more strictly defined requirements are placed on the grain distribution. Grain distribution curves with a high proportion of coarse material or a high proportion of fine material, within a specified grain size limit, are the goal. It is known that a dynamic classifier is used to fractionate powders in mills.

However, the properties of these known devices are increasingly less able to meet the high requirements for grain distribution within the grain spectrum. The disadvantage of these classifier mills is that the integrated dynamic "classifier" is provided with the entire grain spectrum from the mill. This means that particles are fed to the integrated, dynamic "classifier" that are still far too coarse for "classification" in the corresponding grain spectrum. These "coarse" particles prevent some of the already crushed grain, which already corresponds to the desired grain spectrum, from not being fed to the classifier. Such particles are fed back into the grinding process and are crushed again. This inevitably increases the proportion of fine grain in the end product.

The present invention is based on the object of creating devices of the type mentioned above within high-speed "classifying mills" in order to significantly influence the grain spectrum.

-2- According to the invention, this object is achieved in that

1.) An additional, individually adjustable "static" classifier (5) is integrated into the classifier mill.

With this "static" sifter (5) (pre-sifter), particles that are still a multiple of the grain size of the desired finished product are kept out of the sifting zone of the dynamic sifter (4). This measure increases the efficiency of the dynamic sifter (4) as coarse particles no longer hinder the passage of particles that have already been reduced to a size below the upper grain size limit. This enables, for example, the fine grain content of the finished product to be reduced, as particles that have already been removed from the grinding process do not enter the grinding zone (6) again, continue to be reduced and thus lead to a higher fine grain content in the entire grain spectrum.

In order to achieve a higher fine fraction with the classifier mill, the individually adjustable "static" classifier can also be used in reverse.

2.) The grinding track geometry (2) is changed in such a way as to achieve a more targeted rebound direction of the material to be ground. This influences the rebound direction of the particles depending on the inclination of the grinding track recesses and thus leaves them in the grinding zone (6) for a shorter or longer period. This effect has a significant influence on the proportion of fine or coarse material in the finished product.

3.) The grinding elements (3) (grinding stones - blocks - pins) are modified in such a way as to achieve a more targeted rebound direction of the material being ground. Depending on the inclination of the "impact edge" of the grinding elements, the rebound direction of the particles is influenced and thus they remain in the grinding zone for longer or shorter periods.

Further advantages and details of the invention will be explained using the embodiments shown in Figures 1 to 4. Figure 5 shows the current state of the art

Show it :

Fig. 1 The devices according to the invention with the "integrated static sifter" (5) between the grinding zone (6), the grinding track (2), the grinding elements (3), and the dynamic sifter (4), in two different versions. 1.A : grinding disk (7) and dynamic sifter (4), offset by 90 degrees from each other. 1.B : grinding disk (7) and dynamic sifter (4) arranged on the same axis. The sifting blades of the static sifter (5) are arranged so that they can rotate individually around their axis. This means that the setting angle can be changed depending on the requirements of the grain spectrum. This can be done manually on each individual static sifting blade, but also with the help of an adjustable rotating ring that rotates all the blades of the static sifter simultaneously and evenly to the desired angular position.

Fig. 2 The device according to the invention as a top view without housing cover, shown as an example with a dynamic classifier on the same axis. Between the grinding elements (3) located on the grinding disk (7) and the dynamic classifier (4), both of which are rotating at the same time, the static classifier (5) with its individual viewing blades is arranged. The air-product mixture is diverted at these viewing blades and, depending on the arrangement of the viewing blades, the grain size of the particles is influenced in the direction of the dynamic classifier (4).

The geometry of the individual visible sheets can vary depending on the requirements of the finished product. A so-called "sword profile" is shown as an example. Profiles based on the airfoil principle, a teardrop shape and any other profile variants that have a defined, flow-related behavior are also possible.

-A-

Fig. 3 A device according to the invention with a modified grinding path geometry. The optimized grinding path geometry, with obliquely arranged (positively and negatively) impact bars to influence the direction of the rebounding grinding material. Negative arrangement: The grinding material is thrown back in the direction of the grinding zone (6) due to the angle of impact.

Positive arrangement: The material to be ground is thrown out of the grinding zone (6) due to the angle of impact.

The impact strips, or the depth and type of finishes, or the height and type of highlights can vary depending on the product to be processed. Possible profile types are: sawtooth, trapezoidal, semi-circular, long-round and their variants.

Fig. 4 A device according to the invention with modified grinding elements.

Adapted grinding stones (grinding elements) (3) with positive and negative inclination angles to influence the rebound direction.

Shown here in conjunction with two different grinding path geometries, in order to further influence the rebound behavior of the material being ground in the grinding zone.

Fig. 5 Two variants of classifier mills according to the current state of the art. 5.A : Grinding disk (7) and dynamic classifier (4), offset by 90 degrees. 5.B : Grinding disk (7) and dynamic classifier (4) arranged on the same axis.

Claims (4)

K&K GmbH -5- Claims Devices for influencing a grain spectrum in high-speed classifying mills 1.) Device for influencing the grain spectrum in high-speed sifter mills, characterized in that an individually adjustable "static sifter" is integrated between the grinding zone and the dynamic sifting zone, which keeps particles out of this dynamic sifting zone that are significantly larger than the desired limit grain to be separated and thus significantly increases the desired sifting efficiency. 2.) Devices according to claim 1, characterized in that the grinding path geometry is changed so that with obliquely arranged stop bars (positive as well as negative), the particles to be crushed remain longer or shorter in the grinding zone and thus are subjected to the crushing process more or less often. 3.) Devices according to claim 1 and 2, characterized in that the grinding pin geometry (grinding elements) is changed in such a way that with diagonally arranged "beating bars" (positive as well as negative), the particles to be crushed remain in the grinding zone for a shorter or longer time and are thus subjected to crushing more or less often. 4.) Devices according to claims 1 to 3, characterized in that combinations of these devices are used and thus the desired result can be influenced even more.